Sheet separation and prefeed apparatus

ABSTRACT

A bellows, incorporated within a sheet feed roller, is actuated by external actuating apparatus to create a partial vacuum at suction ports in the feed roller periphery. A pivotal pressure pad assembly momentarily presses a sheet stack against the ports, leaving the top sheet adhered to the feed roller which is then rotated to advance the separated top sheet to a prefeed position. Additional actuating apparatus, operating on command, rotates the feed roller through the remainder of a complete revolution to feed the prefed sheet from the apparatus and to reorient the feed roller for the next sheet separation and prefeed cycle.

United States Patent Schrempp et al.

SHEET SEPARATION AND PREFEED APPARATUS [451 Jan. 25, 1972 Primary Examiner-Joseph Wegbreit Attorney-William D. Soltow, Jr., Albert W. Scribner, Martin D. Wittstein and Louis A. Tirelli [5 7] ABSTRACT A bellows, incorporated within a sheet feed roller, is actuated by external actuating apparatus to create a partial vacuum at suction ports in the feed roller periphery. A pivotal pressure pad assembly momentarily presses a sheet stack against the ports, leaving the top sheet adhered to the feed roller which is then rotated to advance the separated top sheet to a prefeed position. Additional actuating apparatus, operating on command, rotates the feed roller through the remainder of a complete revolution to feed the prefed sheet from the apparatus and to reorient the feed roller for the next sheet separation and prefeed cycle.

25 Claims, 13 Drawing Figures PATENTEUJMIZSHTZ 3'637'201 INVENTORS ERNST SCHREMPP CHRISTIAN A. BECK WM; M

ATTORNEY PATENTED m2 5 I972 W; SCH m CH R \STIAN m1. @E'm ERNST ATTORNEY PATENYED MM 1972 M/VENTORS CHRISTIAN A BECK PATENIEU M 872 m/veA/rozegg ERNST SQHREMWZ' CHRISTIAN A. BEWW,

A TTOAQNEY HVVEA/TORS ERNST SCHREMPP CHRlSTIAN A. BECK PATENTED JANZS I972 A TORNEY PATENTEB JAN 2 5 I972 sum B Q? 7 lA/l/ENTORS ERNST SCHREM PP CHRlSTIAM A. BECK ATTORNEY WWENTEB mzsmz mm 6? r //VVENTORS ERNST SCHREMPP CHRISTIIAN A. BECK ATTORNEY REFERENCE TO RELATED APPLICATION Reference is hereby made to the commonly assigned, copending Beck application Ser. No. 74,349 entitled Copy Sheet-Handling Apparatus for Electrostatic Office Copiers, filed Sept. 22, 1970, wherein apparatus herein disclosed is claimed.

BACKGROUND AND OBJECTS OF THE INVENTION The current emphasis in office copier design is speed of operation. Quite naturally, the faster a copier can produce copies the more available it is to subsequent users. Also, a fast copier conserves the time of the operator, who in a small office situation is typically a secretary whose time is valuable. Not only is it important that a copier produce multiple copies rapidly but also that it be capable of producing a single copy without appreciable delay. In a small office situation, probably the most common copy run is that of a single copy.

An additional important designconsideration is the size of the copier. With office space so expensive, it is desirable that the copier be reasonably compact. So called desk copiers are available, however, when placed on a desk top such copiers take up a considerable portion of the work surface.

One way in which to reduce the copier size is to go to precut copy paper in lieu of roll copy paper which must be withdrawn and cut to the size ofthe original sheet during each copy cycle. The precut copy sheets are stacked on a tray or the like and must be individually separated from the stack and fed seriatum through the copier. Reliable separation of a single paper sheet from a stack is not an easy task. If a single copy sheet is not successfully separated and fed, the ensuing copy cycle is a complete waste of time. Moreover, if separation and feeding is performed improperly, the copy sheet may jam up somewhere along its feed path. The copier must then be shutoff and the jam cleared, which may require a service call.

Another problem with the use of precut copy sheets is synchronizing the sheet separation and feeding functions with the actual copying process repeated during each copy cycle. To achieve requisite synchronization, a prefeed" technique is typically resorted to. Generally, this involves separating a single sheet from a copy sheet stack and advancing it to a fixed prefeed position at the conclusion of each copy cycle. Thus, when a next copy cycle is called for a copy sheet is already separated from its stack and is fed through the various copy process station, starting from the prefeed position. This simpli lies the problem of synchronization and also significantly shortens the time required for single copy runs.

Accordingly, an object of the present invention is to provide improved apparatus for reliably separating a sheet of material such as paper from a sheet stack and advancing or feeding the separated sheet to a reference or prefeed position.

A further object is to provide a sheet-handling roller having self-contained means for effective separation of a single sheet from a stack and having further means for participating in the advancement of the separated sheet to the prefeed position.

Yet another object is to provide sheet separation and prefeed apparatus of the above character which is particularly adapted for handling precut copy paper sheets in electrostatic office copiers.

An additional object is tqprovide sheet separation and prefeed apparatus of the above character which is compact, inexpensive to manufacture, reliable and fast in operation.

Other objects of the invention will in part be obvious and in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a self-contained feed roller structure which is externally actuated to effect separation of the top sheet of paper or the like from a sheet stack and to feed the separated sheet to a reference or prefeed position. The feed roller has incorporated therein a compressible bellows which is in communication with one or more suction ports in the feed roller surface. The bellows, by virtue of its inherent resiliency, normally assumes a distended condition and is compressed by external actuator means. While the bellows is compressed, the paper sheet stack is elevated so as to bring the top most sheet into sealed contacting engagement with the roller surface surrounding the suction ports. The compacting pressure on the bellows is then released, thereby creating a partial vacuum sufficient to hold the top sheet against the feed roller, The sheet stack is then lowered, thereby separating the stack from the top sheet which remains adhered to the feed roller. The feed roller is then rotated through a predetermined angle to advance the separated sheet to a desired prefeed position.

The actuator means includes a first cam which is rotated to compress and release the bellows within the feed roller, A second cam is rotated in coordination with the first cam to effect the raising and lowering of the sheet stack by a pivotal pressure pad assembly in timed relation with the actuation of the bellows. Drive means rotating in synchronism with the first and second cams selectively engages the feed roller to effect the requisite incremental rotation thereof for advancing the separated sheet to the prefeed position. In addition, cam actuated detent means insure that the feed roller is properly angularly oriented at the conclusion of a sheet separation and pre feed operation.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. I is a longitudinal sectional view of an electrostatic photocopier employing the apparatus of the present invention;

FIG. 2 is a perspective view of the sheet separation and prefeed apparatus of the invention;

FIG. 3 is a front elevational view, partially broken away, of the apparatus of FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a longitudinal sectional view of the feed roller included in the apparatus of FIG. 2;

FIG. 6 is a side-elevational view, partially broken away, of one of the pressure pads incorporated in the apparatus of FIG.

FIG. 7 is a sectional view taken along line 7-7 of FIG. 3 showing the positions of the various parts at the beginning of a sheet separation and prefeed operation;

FIG. 8 is a sectional view taken along line 7-7 of FIG. 3 showing the positions of the various parts upon achievement of separation of the top sheet from the sheet stack;

FIG. 9 is a sectional view taken along line 7-7 of FIG.-3 showing the positions of the various parts after the separated sheet has been advanced to a prefeed position;

FIG. 10 is a sectional view taken along line 10-10 of FIG, 3 showing the detent means incorporated into the apparatus of the present invention;

FIG. 11 is a fragmentary perspective view of the apparatus for advancing a prefed sheet beyond its prefeed position;

FIG. 12 is a side-elevational view of the actuating means incorporated in the apparatus of FIG. Ill; and

FIG. 13 is an end-elevational view of the actuating means of FIG. 12.

Like reference numerals refer to corresponding parts throughout the several views of the drawings. I

DETAILED DESCRIPTION Referring now to the drawings and first to FIG. I, the apparatus of the present invention is illustrated as being incorporated in an electrostatic photocopier of the direct imaging type which employs copy paper having a photoconductive coating thereon, such as Electrofax paper. It will be appreciated, however, that the apparatus of the present invention has application in other types of office copiers as well as to sheet-handling apparatus generally.

As seen in FIG. I, a stack of precut copy sheets is supported on a tray 12 with the leading edges of the stacked sheets positioned adjacent the sheet-handling apparatus of the present invention, generally indicated at 14. The sheet-handling apparatus 14 includes a sheet separator and sheet feed roller 16 which, in a manner to be described, is employed to separate the top sheet from the copy sheet stack 10 and then advance the separated sheet to a prefeed position where its leading edge is engaged between feed roller 16 and an idler feed roller I8. As will be seen, separation of the top sheet from the sheet stack 10 is effected, in accordance with the invention, by adapting the feed roller 16 with means for creating a partial vacuum at suction ports formed in its peripheral surface. A pressure pad assembly, generally indicated at 20, is actuated to lift the leading edges of the stack 10 so that the upper surface of the top sheet is pressed against the periphery of the feed roller 16 in sealing relation to the suction ports therein. A partial vacuum is then created at these ports to adhere the top sheet to the feed roller periphery which is then readily separated from the rest of the stack 10 merely by pivoting the pressure pad assembly 20 away from the feed roller I6.

Once separation of the top sheet from the sheet stack 10 has been effected, feed roller 16 is then driven through an increment of rotation such that the leading edge of the separated sheet is advanced through the nip of feed roller 16 and idler roller 18 to a prefeed position. The presence of a prefed sheet is sensed by a switch 22.

As contemplated by the present invention, sheet separation and prefeed occurs at the conclusion of each copy cycle. .Upon the initiation of the next copy cycle, the prefed sheet is then advanced to and through the various copy processing stations. Thus, as seen in FIG. 1, a prefed sheet, indicated at 24, is advanced from its prefeed position by rotation of feed roller I6 through a suitable corona charger 26. Rotation of feed roller 16 continues until the leading edge of copy sheet 24 is engaged between a set of feed rollers 28. During advancement of a prefed sheet beyond its prefeed position, the sheet-handling apparatus 14 is controlled by actuating means, generally indicated at 30.

To initiate operation of the actuating means 30, the copier is turned on to provide continuous drive to feed rollers 32 positioned in a document feed path. A document 36 to be copied is inserted into the nip of feed rollers 32 and the passage of its leading edge therebeyond trips a switch 34 which signals the actuating means 30 into operation. A prefed copy sheet 24 is then advanced by rotation of the feed roller 16 through the corona charger 26 and its leading edge arrives at the nip of feed rollers 28 substantially at the same time as does the leading edge of the original document 36 being fed by feed rollers 32. The copy sheet 24 and the original document sheet 36 then pass through an imaging station, generally indicated at 38, where the copy sheet is selectively discharged by light to transform the image borne by the original document to a latent electrostatic image on the surface of copy sheet 24. From the imaging station 38, the juxtaposed document sheet and copy sheet are fed by feed rollers 40 to feed rollers 42 which are also adapted to separate the sheets such that they may thereafter follow separate paths. lmmenently suitable juxtaposed sheet feeding and separating apparatus is disclosed in copending application of Beck and Tomasch entitled Separator for juxtaposed Sheets, Ser. No. 23,215, filed Mar. 27, 1970 and assigned to the assignee of the present application. The copy sheet 24 and the document sheet 36 are selectively acted upon by operation of the separator feed rollers 42 to develop a separation therebetween, such that the document sheet passes over a separator guide plate 43 while the copy sheet passes under the separator guide plate. The document sheet 36 follows a path defined by guide plates 44 for return to the operator. The copy sheet 24 passes over a guide plate 45 to a development station, generally indicated at 46, where the latent electrostatic image carried thereby is developed into a visible image. The developed sheet precedes along a path defined by guide plates 48 for delivery to the operator.

The feed roller I6, as best seen in FIG. 5, consists of an elongated cylinder 50 with a detent disc 52 secured in its left end and an end cap 54 secured in its right end. A partition 56 is secured within cylinder 50 by screws 57. A bellows 58, formed of a suitable material such'as metal, is mounted and hermetically sealed at its left end to one side of partition 56.

The other end of bellows 58 is sealed off by an end plate 60.

Bellows 58 is formed such that it normally assumes an extended condition as indicated in phantom. 1

A pair of tubular fittings 62 extend through partition 56 and communicate with the interior of bellows 58. A pair of fittings 64 are secured in the wall of cylinder 50 and are coupled to fittings 62 by separate lengths of flexible tubing 66. The

fittings 64 thus provide ports 65 at axially aligned points in the periphery of cylinder 50 which are in pneumatic communication with the interior of bellows 58. It will be understood that while two ports 65 are shown in the illustrated embodiment,

an additional number of ports may be provided. Also, a single port 65 may be sufficient for effecting sheet separation and be described, the top sheet of the sheet stack 10 is adequately sealed against the material surrounding the ports 65 by operation of the pressure pad assembly 20 (FIG. I) at the time a negative pressure or suction is created at the ports 65 by operation of the bellows 58. It will be appreciated that certain elastomeric materials may be conducive to both functions, thus eliminating the need for inserts 70.

Still referring to FIG. 5, the inserts 70 are apertured so as to communicate with the ports 65 provided by fittings 64 and is also recessed to provide a suction cuplike shape for improved adherence of a paper sheet thereto upon actuation of the bel lows 58.

As seen in FIGS. 3 and 5, a coaxial stub shaft 74, secured to detent disc 52, serves to mount the left end of feed roller 16; the shaft being journaled in an upright side frame 76 secured to a base 77. The other end of feed roller 16 is rotatably mounted by a sleeve 78 secured in a central bore through end cap 54 and journaled by a bushing mounted by side frame member 82, also secured to base 77 (FIG. 3). An elongated actuating pin 84 extends through sleeve 78 with its left end fastened to end plate 60 of bellows 58. Actuating pin 84 carries an integral cam follower disc 86 at a point beyond bushing 80; the cam follower disc being acted upon by a sheet separation and prefeed actuating mechanism to be described.

As previously noted, the bellows 58 is constructed such that its normal unconstrained condition is that indicated in phantom in FIG. 5. When the bellows 58 is so extended, pin 84 and cam follower disc 86 are pushed to the right, assuming the phantom position shown in FIG. 5. When the cam follower disc 86 is pushed to the left, pin 84 acts to compress the bellows 58. At this point, as will be seen, the top sheet of the stack 10 is brought into sealing engagement about ports 65, whereupon the bellows is released to assume its extended position. This is effective to create a negative pressure or suction at ports 65 sufficient to securely hold the paper sheet thereto.

Turning now to FIG. 2, the sheet separation and prefeed actuating mechanism is generally indicated at 88. Mechanism 88 is powered from a drive train consisting, in part, of gears 09 and 90, shaft III and gears 02 and 93 (FIG. 3) which are all driven as long as the copier is turned on. A shaft 96 for gear 93 constitutes the input shaft to a one revolution clutch 95 which is engaged by actuation of a solenoid I00. Thus, each time the solenoid I is actuated, it causes the clutch 00 to couple its input shaft 06 to its output shaft I02 for one complete revolution, after which the two shafts are decoupled. Output shaft 102 carries a radial disc cam I04, a helical cam I06 and a disc I08 having a spur gear segment I10 formed in its periphery and an internal annular cam track III with a raised cam segment I14 formed therein. It is thus seen that upon engagement of clutch 90, cam I04, cam I06 and disc I00 are driven through one complete revolution.

As seen in FIGS. 2 and 5, radial disc cam I04 acts on a cam follower II6a carried by a cam follower arm I116 which is secured at its lower end on a shaft IIO rotatably mounted by brackets I119 (FIG. 3). A hook-shaped actuator I20, secured on the left end of shaft IIO, acts on an actuator pin I22 to downwardly pivot a carriage I24, included in the pressure pad assembly 20 (FIG. I). Carriage I24 is pivotally mounted on a fixed shaft I26, seen in FIGS. I and II. A spring I20 biases cam follower II6a against the periphery of radial disc cam I04.

Still referring principally to FIGS. 2 and 3, the carriage I24 supports a pair of brackets 150, secured thereto by bolts I31. The upper end of each bracket I30 is bent laterally outward so as to support a pressure pad I32. As seen in FIG. 6, each pressure pad, which is formed of a suitable material such as metal, has a threaded shaft 1132a which extends through a hole in the lateral portion of bracket I30 and receives a nut I33 clamping the pressure pad thereto. The face of each pressure pad is formed on a radius corresponding to the radius of curvature of the gripper rings 60 (FIG. 2). A recess I32b is formed in the front surface of the pressure pads so as to leave a rim 132a which acts as the pressure transmitting surface for pressing the top sheet of the sheet stack I0 against the surface of insert 70 surrounding ports 65 (FIG. As is seen in FIGS. I and 7 through 9, the leading edges of the sheet stack I0 lie in the area between feed roller I6 and the pressure pads I32. The carriage I24 is normally urged toward the feed roller I6 by springs I36 (FIG. 3). Thus, the pressure pads I52 engage the under-surface of the bottom sheet of the sheet stack and lift the leading ends of the stacked sheets upwardly to bring the upper surface of the top sheet adjacent its leading edge into sealing engagement about the ports 65.

As is seen in FIG. 2, the carriage I24 carries lateral extensions which are bent upwardly and extend toward the feed roller and curve downwardly to provide outrigger elements I30 which act to support the lateral edge portions of the sheet stack as the leading edge portions therefore are lifted upwardly toward the feed roller I6 by clockwise pivotal movement of the carriage I24, Outrigger elements I30 also serve as supports for stop elements I40 which extend upwardly in abutting engagement with the leading edges of the sheet stack I0. These stop elements I40 serve to prevent forward movement of the underlying sheets in the sheet stack as the separated top sheet is advanced to its prefeed position and beyond by rotation of the feed roller I6.

Still referring principally to FIGS. 2 and 5, the helical cam I06 carried on shaft I02 acts on the cam follower disc 06 which was described in connection with FIG. 5. In the positions of the various parts shown in FIG. 2, which are their posioperation, the trailing end I06a of helical cam I06, assuming counterclockwise rotation thereof, engages the cam follower disc 06 thereby compressing bellows 50 through actuating rod 04. This initial condition is also seen in FIG. 4. After the helical cam I06 is rotated through a small increment of counter clockwise rotation, cam follower 06 is released, permitting the bellows 50 to extend, thereby creating a suction at ports 65. It is seen that as helical cam I06 continues to rotate, the leading, laterally offset and I06b of the cam engages the cam follower disc 06 to cause the bellows 55 to be gradually compressed to the state shown in FIG. 5.

As is seen in FIG. 2, at the beginning of a sheet separation and prefeed operation and before the bellows 58 is released by helical can I06, cam follower 116a is riding in the valley 104a of radial disc cam I04. Actuator I20 is thus located and held in its extreme clockwise position by spring I20, thereby permitting the carriage I24 to be positioned by spring I36 adjacent the feed roller I6 and press the top sheet of the stack 10 into sealing relation with the ports 65. The stack I20 is oriented on its shaft 110 such that the pressure pads 132 are always capable of pressing the top sheet against the ports 65 regardless of the number of sheets in the sheet stack I0. As cams I04 and I06 begin to rotate, the first thing that happens is that the cam I06 releases the bellows 50 which then creates v the suction at ports 65. The suction or negative pressure at ports 65 is effected to hold the top sheet which is pressed thereagainst by the pressure pads I32 acting through the underlying sheets in the sheet stack. As the radial disc cam I04 continues to rotate, cam follower arm 116 to rock counterclockwise bringing actuator 120 into depressing engagement with the actuator rod 122. The carriage I24 is then rocked in the counterclockwise direction dropping the leading edges of the underlying sheets in the sheet stack I0 away from the feed roller I6. The top sheet thus becomes separated from the remainder of the stack by virtue of the suction created at ports 65.

Having separated the top sheet from the sheet stack, it remains to advance the separated sheet to a prefeed position. Prefeed is accomplished by rotation of the feed roller by engagement with the gear segment 110 formed on the periphery of disc I00 rotating with cams I04 and I06 on shaft 102. Rather than have mating gearteeth formed on the feed roller I6, it is preferred to provide a ring I50 of rubber or other suitable elastomeric material secured to end cap 54 (FIG. 5) which is engaged by the gear segment I I0.

As the disc I00 rotates counterclockwise, a cam follower I52 carried by a cam follower arm 154 is rocked downwardly by cam segment II4. The other end of cam follower arm I54 is secured on an elongated shaft I56 which is appropriately mounted by means not shown. The other end of shaft I56 carries a detent release arm I58 which supports at its free end a tions at the beginning of each sheet separation and prefeed pawl adapted to operate against detent disc 52 secured to the left end of feed roller 16. The detent disc 52, as best seen in FIG. I0, is formed having a pair of radial walls 520 and 52b. Returning to FIG. 2 it is seen that as: disc I08 rotates counterclockwise, cam follower arm I54 disengages the pawl 160 from the radial wall 520 of detent disc 52. This frees the feed roller I6 for clockwise rotation as the gear segment teeth I10 bite into the ring I50. Before the last tooth of gear segment IIO rotates out of driving engagement with the ring 150, cam segment II4 terminates, thereby permitting the pawl I60 to rise back into engagement with the periphery of detent disc 52 before it encounters radial wall 5%; this movement being induced by return spring I62. As radial wall 52b encounters pawl 160 to terminate further rotation of feed roller 116, the last tooth of gear segment Ili0 still drivingly engages rubber ring I50. This insures that the feed roller I6 is angularly oriented at the termination of the prefeed operation precisely at the point where radial wall 52b is engaged by pawl I60. It is for this reason that an elastomeric ring I50 is preferred over a gear ring as it would require stringent manufacturing tolerances to insure that the gears disengage precisely at the point where the pawl I60 engages the radial wall 52b of detent disc 52. It will be appreciated if the drive of feed roller I6 terminates short of the detent position determined by radial wall 52!), the separated sheet will not be prefed to the desired prefeed position. On the other hand, if the drive terminates after the tip I60 engages radial wall 52b, an interference situation is created which would result in damage to various parts of the apparatus. Rubber ring I50, however, yields to release the last geartooth of segment IIO as the pawl I60 inhibits further feed roller rotation. This slippage insures proper angular orientation of the feed roller at the conclusion of the prefeed operation.

The positions of the various parts of the sheet-handling apparatus 14 at various stages in the sheet separation and prefeed operation are shown in FIGS. 7 through 0. In FIG. 7 the parts are shown in their positions at the beginning of a sheet separation and prefeed operating cycle, which positions are also illustrated in the perspective view of FIG. 2. Thus, the pressure pads 132 are pressing the leading edge portions of the sheet stack against the feed roller 16 under the force of the carriage springs 136 (FIG. 3). Solenoid 100 is pulsed and the one revolution clutch 98 is engaged to rotate its output shaft 102 through a complete revolution. The first event is the creation of a suction at each of the feed roller ports 65 caused by the disengagement of the helical cam trailing edge 106a from the cam follower disc 86. As previously noted, the bellows 58 springs to its extended condition; the resulting internal expansion of the bellows being effective to create the suction or negative pressure at ports 65. Thereafter, radial disc cam 104 operates through cam follower arm 116 and actuator 120 to pivot the carriage 124 downwardly to remove the underlying sheets of the stack from the feed roller 16. The top sheet 10a, however, is held against the feed roller ports 65 by the suction thereat. This condition is shown in FIG. 8.

Also at this time, the cam segment 114 carried by disc 108 acts through cam follower arm 154 and detent release arm 158 to remove pawl 160 from engagement with the radial wall 52a of detent disc 52. The feed roller is thus free to be rotated by gear segment 110 in the clockwise direction through an angle A (FIG. 10) of approximately 100 As seen in FIG. 9, the separated top sheet 10a of the sheet stack 10 has been advanced through the nip of idler roller 18 and the gripper rings 68 on feed roller 16 to a prefeed position. During prefeed of the top sheet 10a, stop elements 140 prevent the underlying sheets of the stack from being dragged forward by prefeeding movement of top sheet 10a. Switch 22 is actuated by the top sheet as it is advanced to the prefeed position and thus senses that a sheet has been successfully prefed.

As the clutch output shaft 102 continues to rotate through the remainder of its complete revolution, helical cam 106 reengages cam follower disc 86 with its leading edge 106k to gradually compress bellows 58. This action does not disturb the prefed top sheet 10a since it is engaged in the nip of feed roller 16 and idler roller 18. As radial disc cam 104 continues to rotate through to the conclusion of its complete revolution, cam follower 116a again rides into valley 104a, whereupon the carriage springs 136 pivot the carriage 124 in the clockwise direction bringing the pressure pads 132 upwardly to press the underlying sheets of the sheet stack againstthe feed roller 16. Thus, the carriage 124 assumes the position shown in FIG. 7, while the feed roller 16 remains in the orientation shown in FIG. 9.

Having successfully prefed a top sheet 10a, it now remains to advance the prefed sheet on through the copier process stations and also to return the feed roller 16 to its proper angular orientation for the beginning of another sheet separation and prefeed operation. To this end, the actuating means 30 mentioned in connection with FIG. 1 and illustrated in detail in FIGS. 11 through 13 is uniquely adapted. As best seen in FIG.

13, the actuating means 30 includes a drive pulley 170 which is continuously rotated by a drive belt 172 for as long as the copier is turned on. Pulley 170 is mounted on a shaft 174 which serves as the input shaft to a one revolution clutch 176. The clutch output shaft 178 is adapted to rotate a radial disc cam 180, a disc 182 and a second radial disc cam 184. As seen in FIG. 13, a solenoid 186 is pulsed to pull down on a link 188 through a complete revolution, as driven by a clutch input shaft 174. At the completion of a revolution, detent ledge 194a again encounters the stop 190a in arm 190 to inhibit further counterclockwise rotation.

As seen in FIGS. 11 and 12, radial disc cam 180 acts on a cam follower 200 carried by a cam follower arm 202 which is secured at its other end on a shaft 204. The other end of shaft 204 carries a sector gear 206 which engages a spur gear 208 carried on a shaft 210 supported by a U-shaped bracket 212. The other end of shaft 210 carries an actuator arm 214 which is oriented in actuating relation to an actuator pin 216 carried by carriage 124. Cam follower 200 is urged against the periphery of radial disc cam 18 by a return spring 218 acting on a return spring arm 220 secured on shaft 204.

It is thus seen that when radial disc cam 180 is rotated in the counterclockwise direction, cam follower arm 202 is rocked downwardly as the cam follower 200 rides up on the rise 180a. This results in clockwise rotation of actuator arm 214 and downward pivotal movement of carriage 124 to remove the pressure pads 132 from the vicinity of the feed roller 16. It will be recalled that the orientation of the radial disc cam 104 in FIG. 2 at the conclusion of a prefeed operation is such that the pressure pads are permitted to press the leading edges of the sheet stack against the feed roller periphery. Thus, as the prefed sheet is advanced beyond its prefeed position, the pressure pads 132 must again be removed from the periphery of the feed roller so as not to interfere with the feeding of the prefed sheet. Radial disc cam 180 serves this purpose.

Returning to FIGS. 11 and 12, radial disc cam 184 acts on a cam follower 224 carried by a cam follower arm 226 which is urged in the counterclockwise direction by return spring 227. Cam follower arm 226 is pivotally mounted on a shaft 228 and carries a pin 230 which is received in an elongated slot 232 formed in the free end of detent release arm 158. This lost motion connection permits the pawl to be released from detent disc 52 by rotation of disc 108 (FIG. 2) or radial disc cam 184. Thus, to advance a prefed sheet 10a beyond its prefeed position, cam follower 224 rides up on cam rise 118411 upon rotation of radial disc cam 184 to free pawl 160 from radial wall 52b. Cam rise 184a terminates at 18412 and the pawl is permitted to assume a position in intercepting relation to radial walli 52a as feed roller 16 is rotated in the clockwise direction.

To drivingly rotate feed roller 16, a spur gear 240 is secured on shaft 74 extending from the left end of the feed roller. As disc 182 is rotated through a complete revolution, gear segment teeth 182a formed in the periphery thereof engage spur gear 240, thus imparting clockwise rotation to feed roller 16. From FIG. 1 it is seen that such rotation advances a prefed sheet through corona charger 26 to the nip of feed rollers 28. The length of gear segment 182a is such that feed roller 16 is rotated through slightly less than an angle B (FIG. 10) which, when added to angle A, constitutes a complete revolution of the feed roller necessary to reorient it to its angular position at the beginning of a sheet separation and prefeed operation. This angular position is determined by the engagement of pawl 160 with radial wall 520 of detent disc 52.

To avoid an interference situation, gear segment 182a disengages from spur gear 240 before the feed roller 16 has been rotated completely through angle B. The final increment of feed roller rotation to bring radial wall 52a of detent disc 52 into abutting engagement with pawl 160 is induced by a column spring 244 which is secured to a face of spur gear 208 as best seen in FIG. 11. The free end of columnspring 244 moves upwardly into engagement with a ledge 246 formed on the periphery of detent disc 52 as cam follower 200 rides off the termination b of cam rise 180a formed in radial disc cam 180 near the conclusion of a complete rotation thereof. Column spring 244 acts against ledge 246 to rotate feed roller 16 through a very small angle to the point where pawl 160 engages radial wall 520, thereby finally positioning the feed roller for the next sheet separation and prefeed operation.

It will be noted particularly from FIG. l2, that the prefed sheet feeding rotation of the feed roller 116 occurs within the first approximately 60 of rotation of the gear segment disc 182. As seen from FIG. 3, the sheets being separated, prefed and then fed are significantly longer in length than the circumference of feed roller lb. thus a complete revolution of the feed roller is not sufficient to clear the top sheet llfia from the sheet-handling apparatus M. A complete feed roller revolution is sufficient however to advance a copy sheet from its position on the sheet stack 110 to the nip of feed rollers 2%. At this point, feed rollers 23, in effect, act to pull the top sheet without further rotation of feed roller 116 as the sheet is cleared from the sheet-handling apparatus ll tl. In order to facilitate this operation, a Teflon pad 250 (FIG. 2) is embedded in each gripper ring 6ft carried by feed roller to. The Teflon pads 250 are positioned such that they are aligned with idler feed roller Iii when the feed roller 16 is oriented for the beginning of a sheet separation and prefeed operation which is also its orientation during the time that a prefed sheet is being cleared from the sheet-handling apparatus M by feed rollers 28. The Teflon pads 250 thus provide a relatively frictionless surface over which the sheets may be dragged, and thus damage to the sheet is avoided.

An additional function of radial disc cam 184 is to actuate a switch 252 seen in FIGS. Ill and 12. Switch 252 has a switch actuating arm 254 which is actuated by the raised cam surface 1184a of radial disc cam 11M. This switch serves as an interlock switch which is used to enable the actuation of solenoid lllltl to initiate a sheet separation and a prefeed operation. While the actuating arm 254 of switch 252 bears against the lower cam surface time of radial disc cam rat, solenoid 100 is disabled and a sheet separation and prefeed operation cannot be initiated.

From the foregoing description, it is seen that the operating sequence, in summary, is as follows. Assuming a separated sheet has been prefed to the prefeed position, preparatory to the next copy cycle, the copier is turned on and on original document 316 is inserted into the nip of feed rollers 32 (FIG. 1). Switch Ml is triggered by the passage of the leading edge of the document beyond feed rollers 32 and, as a result, solenoid m6 (FIG. 13) is energized to engage one revolution clutch 1176. The prefed sheet lltla which is in the position shown in FIG. 9, is then fed by rotation of feed roller to through the corona charger 2s and into the nip of feed rollers 28, arriving there at the same time as does the leading edge of document sheet 36. The feed roller l6 remains in the orientation shown in FIGS. ii and 7, while the sheet 10a is cleared from the sheethandling area by the feed rollers 28. Near the completion of the full 360 rotation of radial disc cam 1%, the actuating arm 254 of switch 252 rides up on the raised cam surface 184 a thereof. This occurs just after the time that the sheet 10a has cleared the area of the sheet-handling apparatus 14 and the resulting actuation of switch 252 triggers the solenoid llillll to initiate a sheet separation and prefeed operation. Preferably, switch 22 is connected in series with switch 252 so that solenoid 16M) cannot be triggered by switch 252 if a prefed sheet 1100 has not cleared the sheet-handling apparatus. As previously described, the sheet separation and prefeed actuating means 88 then operates to separates and advance a top sheet 100 from the sheet stack llil and advance it to the prefeed position shown in FIG. 9.

Switch 22 senses whether or not a sheet is in the prefeed position preparatory the initiation of the next copy cycle. If when the copier is turned on and switch 22 senses that no sheet is in the prefeed position, such as would occur after the copy paper supply has been exhausted and the stack 110 is replenished, the control logic may be designed such that switch 22 initiates a succession of sheet separation and prefeed operations until a sheet iltla is successfully separated and prefed. It will be observed that whatever the initial orientation of feed roller llb, it will be indexed through an increment equal to angle A (FIG. llti) each time the sheet separation and pre feed actuating mechanism 855 is triggered by solenoid tilt).

llilt During one of these indexing steps, pawl 160 engages radial wall 52a to stop the feed roller 16 at the proper orientation for the initiation ofa sheet separation and prefeed operation. This is permitted since gear segment 110 will slip on ring 150 after feed roller rotation has been inhibited] by pawl 1160. With the next pulsing of solenoid 100, a top sheet ll0a is separated and prefed, whereupon switch 22 is tripped and the copier is then prepared for a normal copy cycle. v

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described the invention, what is claimed as new and desire to secure by Letters Patent is:

1. An assembly for separating sheets from a sheet stack, said assembly comprising, in combination:

A. a cylinder;

B. a chamber mounted within said cylinder;

C. means forming at least one port in the wall of said cylinder,

1. said port communicating with the interior of said chamber;

D. actuating means operatively coupled to said chamber and extending externally of said cylinder,

-I. said actuating means capable of being selectively acted upon at a point external of said cylinder to cause expansion and compression of said chamber,

2. whereby to create a negative pressure at said port sufficient to hold the top sheet of a sheet stack against said port in separated relation to the underlying sheets of the stack; and

E. means extending from each end of said cylinder for mounting said cylinder for rotation about its longitudinal axis.

2. The assembly defined in claim 1, wherein said bhamber is 4 in the form ofa bellows.

3. The assembly defined in claim 2, wherein said bellows is normallyresiliently biased to an expanded state and said actuating means is adapted to compress said bellows and then release said bellows for expansion to said expanded state to thereby create said negative pressure.

ll. The assembly defined inclaim 3, wherein said actuating means is in the form of a rod mounted for reciprocating movement by an end cap for said cylinder,

1 the inner end of said rod bearing against said bellows.

5. The assembly defined in claim 2, which further includes:

A. annular drive engageable means mounted on said cylinder facilitating driven rotation thereof about its longitudinal axis to advance a separated top sheet relative to the sheet stack.

6. The assembly defined in claim 5, which further includes:

A. at least one resilient annular member mounted on said cylinder for .coaction with an idler roller to feed a separated top sheet upon rotation of said cylinder via said drive engageable means.

7. The assembly defined in claim 6, wherein said annular member is apertured at a point aligned with said port.

ii. The assembly defined in claim 2, which further includes:

A. detent means carried by said cylinder, said detent means port relative to the sheet stack.

9. Apparatus for separating a top sheet from a sheet stack and advancing the separated top sheet to a predetermined position, said apparatus comprising, in combination:

A. a feed roller mounted for rotation about its longitudinal axis, said feed roller having I. a chamber accommodated therein,

2. means forming at least one port in the peripheral wall thereof communicating with said chamber, and

1. serving to define a predetermined angular orientation of said cylinder required to appropriately position said 3. an actuator operatively coupled to said chamber and extending externally of said feed roller;

B. means supporting the sheet stack adjacent said feed roller;

C. a pressure pad assembly operable to move the sheet stack relative to said feed roller to press a surface portion of the top sheet into sealing relation with said port; and

D. Control means for 1. operating said pressure pad assembly to press the top sheet into sealing relation with said port,

2. operating said actuator to cause expansion of said chamber and thereby create a negative pressure at said port sufficient to hold the top sheet thereagainst in separated relation to the sheet stack, and

3. rotating said feed roller to advance the separated top sheet to the predetermined position.

10. The apparatus defined in claim 9, wherein said chamber is in the form of a bellows which normally assumes an expanded condition and is released from a compressed condition by said control means via said actuator to create said negative pressure at said port.

11. The apparatus defined in claim 10, wherein there are at least two of said ports in longitudinal alignment.

[2. The apparatus defined in claim 10, wherein said control means includes:

1. A first rotatable cam for operating said pressure pad assembly,

2. a second cam rotating in synchronism with said first cam and acting on said actuator to selectively apply a compressive force to said bellows, and

3. drive means rotating in synchronism with said first and second cams for selectively drivingly engaging said feed roller to rotate same.

13. The apparatus defined in claim 12, wherein said drive means included in said control means is in the form of a spur gear segment, and said feed roller carries a resilient ring positioned for engagement by the teeth of said spur gear segment.

14. The apparatus defined in claim 12, wherein said first and second cams and said drive means are rotated on a common shaft, said common shaft being rotated through a complete revolution for each operating cycle of the apparatus.

15. The apparatus defined in claim 12, wherein said feed roller carries a detent element and said control means further includes detent means for selectively engaging said detent element to establish the initial and final angular orientations of said feed roller during an operating cycle of the apparatus.

16. The apparatus defined in claim 9 wherein said feed roller carries at least one resilient traction ring for coacting with an idler feed roller to assist in advancing the separated top sheet to the predetermined position.

17. The apparatus defined in claim 16, wherein said traction ring is axially aligned with said port, the portion of said traction ring overlying said port being removed.

18. The apparatus defined in claim 9, wherein said pressure pad assembly includes:

1. a pressure pad aligned with said port and adapted to lift the sheet stack and press the top sheet against said port, and

2. a stop element adapted to engage the leading edges of the underlying sheets of the stack as the separated top sheet is advanced to the predetermined position.

19. For use in an electrostatic copier, apparatus for separatinto sealing relation with said port and D. control means for operating said carriage and said suction generating means to retain the top sheet against said feed roller by suction as said carriage is moved away from 1 said feed roller to separate the top sheet from the underlying sheets of the stack and for rotating said feed roller to advance the separated top sheet to the prefeed position.

20. The apparatus defined in claim 19, wherein said suction generating means is in the form of a bellows which normally springs to an expanded condition, and an actuating rod mounted by said feed roller for reciprocating movement, said control means acting on said rod to compress and then release said bellows, thereby producing the suction at said port.

21. The apparatus defined in claim 20, wherein said control means includes:

1. a shaft adapted to execute a complete revolution during each operating cycle of the apparatus,

2. a first cam on said shaft operatively coupled to said carrlage,

3. a second cam on said shaft operatively coupled to said actuating rod, and

4. drive means on said shaft for selectively engaging and rotating said feed roller.

22. The apparatus defined in claim 21, wherein said feed roller carries and annular detent element, and said control means further includes detent release means actuated by a third cam on said shaft to selectively engage said detent element to establish the initial and final angular orientations of the feed roller during an operating cycle of the apparatus.

23. The apparatus defined in claim 21, wherein said drive means comprises a spur gear segment and said feed roller carries a resilient ring positioned for yieldable during engagement by the teeth of said spur gear segment. I I

24. The apparatus defined in claim 20, wherein said feed roller carries at least one traction ring adapted for coaction with an idler feed roller to assist in prefeeding the separated top sheet, said traction ring overlying said port and being apertured to expose said port at the periphery thereof.

25. The apparatus defined in claim 20, wherein said carriage includes:

1. a pressure pad aligned with said port,

2. a stop element engaging the leading edges of the underlying sheets of the stack to inhibit advancement thereof during prefeeding of the separated top sheet, and

3. outrigger elements for supporting the lateral edges of the sheet stack. 1 

1. An assembly for separating sheets from a sheet stack, said assembly comprising, in combination: A. a cylinder; B. a chamber mounted within said cylinder; C. means forming at least one port in the wall of said cylinder,
 1. said port communicating with the interior of said chamber; D. actuating means operatively coupled to said chamber and extending externally of said cylinder,
 1. said actuating means capable of being selectively acted upon at a point external of said cylinder to cause expansion and compression of said chamber,
 2. whereby to create a negative pressure at said port sufficient to hold the top sheet of a sheet stack against said port in separated relation to the underlying sheets of the stack; and E. means extending from each end of said cylinder for mounting said cylinder for rotation about its longitudinal axis.
 2. means forming at least one port in the peripheral wall thereof communicating with said chamber, and
 2. operating said actuator to cause expansion of said chamber and thereby create a negative pressure at said port sufficient to hold the top sheet thereagainst in separated relation to the sheet stack, and
 2. a stop element adapted to engage the leading edges of the underlying sheets of the stack as the separated top sheet is advanced to the predetermined position.
 2. whereby to create a negative pressure at said port sufficient to hold the top sheet of a sheet stack against said port in separated relation to the underlying sheets of the stack; and E. means extending from each end of said cylinder for mounting said cylinder for rotation about its longitudinal axis.
 2. The assembly defined in claim 1, wherein said chamber is in the form of a bellows.
 2. a second cam rotating in synchronizm with said first cam and acting on said actuator to selectively apply a compressive force to said bellows, and
 2. a first cam on said shaft operatively coupled to said carriage,
 2. a stop element engaging the leading edges of the underlying sheets of the stack to inhibit advancement thereof during prefeeding of the separated top sheet, and
 3. outrigger elements for supporting the lateral edges of the sheet stack.
 3. a second cam on said shaft operatively coupled to said actuating rod, and
 3. drive means rotating in synchronism with said first and second cams for selectively drivingly engaging said feed roller to rotate same.
 3. The assembly defined in claim 2, wherein said bellows is normally resiliently biased to an expanded state and said actuating means is adapted to compress said bellows and then release said bellows for expansion to said expanded state to thereby create said negative pressure.
 3. rotating said feed roller to advance the separated top sheet to the predetermined position.
 3. an actuator operatively coupled to said chamber and extending externally of said feed roller; B. means supporting the sheet stack adjaCent said feed roller; C. a pressure pad assembly operable to move the sheet stack relative to said feed roller to press a surface portion of the top sheet into sealing relation with said port; and D. Control means for
 4. The assembly defined in claim 3, wherein said actuating means is in the form of a rod mounted for reciprocating movement by an end cap for said cylinder,
 4. drive means on said shaft for selectively engaging and rotating said feed roller.
 5. The assembly defined in claim 2, which further includes: A. annular drive engageable means mounted on said cylinder facilitating driven rotation thereof about its longitudinal axis to advance a separated top sheet relative to the sheet stack.
 6. The assembly defined in claim 5, which further includes: A. at least one resilient annular member mounted on said cylinder for coaction with an idler roller to feed a separated top sheet upon rotation of said cylinder via said drive engageable means.
 7. The assembly defined in claim 6, wherein said annular member is apertured at a point aligned with said port.
 8. The assembly defined in claim 2, which further includes: A. detent means carried by said cylinder, said detent means
 9. Apparatus for separating a top sheet from a sheet stack and advancing the separated top sheet to a predetermined position, said apparatus comprising, in combination: A. a feed roller mounted for rotation about its longitudinal axis, said feed roller having
 10. The apparatus defined in claim 9, wherein said chamber is in the form of a bellows which normally assumes an expanded condition and is released from a compressed condition by said control means via said actuator to create said negative pressure at said port.
 11. The apparatus defined in claim 10, wherein there are at least two of said ports in longitudinal alignment.
 12. The apparatus defined in claim 10, wherein said control means includes:
 13. The apparatus defined in claim 12, wherein said drive means included in said control means is in the form of a spur gear segment, and said feed roller carries a resilient ring positioned for engagement by the teeth of said spur gear segment.
 14. The apparatus defined in claim 12, wherein said first and second cams and said drive means are rotated on a common shaft, said common shaft being rotated through a complete revolution for each operating cycle of the apparatus.
 15. The apparatus defined in claim 12, wherein said feed roller carries a detent element and said control means further includes detent means for selectively engaging said detent element to establish the initial and final angular orientations of said feed roller during an operating cycle of the apparatus.
 16. The apparatus defined in claim 9 wherein said feed roller carries at least one resilient traction ring for coacting with an idler feed roller to assist in advancing the separated top sheet to the predetermined position.
 17. The apparatus defined in claim 16, wherein said traction ring is axially alligned with said port, the portion of said traction ring overlying said port being removed.
 18. The apparatus defined in claim 9, wherein said pressure pad assembly includes:
 19. For use in an electrostatic copier, apparatus for separating the top sheet from a sheet stack and prefeeding the separated top sheet to a predetermined prefeed position, said apparatus comprising, in combination: A. a feed roller having suction generating means self-contained therein for producing a suction at a port formed in the feed roller peripheral surface; B. means supporting the sheet stack; C. carriage means operable to move the sheet stack toward the feed roller and press a surface portion of the top sheet into sealing relation with said port; and D. control means for operating said carriage and said suction generating means to retain the top sheet against said feed roller by suction as said carriage is moved away from said feed roller to separate the top sheet from the underlying sheets of the stack and for rotating said feed roller to advance the separated top sheet to the prefeed positiOn.
 20. The apparatus defined in claim 19, wherein said suction generating means is in the form of a bellows which normally springs to an expanded condition, and an actuating rod mounted by said feed roller for reciprocating movement, said control means acting on said rod to compress and then release said bellows, thereby producing the suction at said port.
 21. The apparatus defined in claim 20, wherein said control means includes:
 22. The apparatus defined in claim 21, wherein said feed roller carries and annular detent element, and said control means further includes detent release means actuated by a third cam on said shaft to selectively engage said detent element to establish the initial and final angular orientations of the feed roller during an operating cycle of the apparatus.
 23. The apparatus defined in claim 21, wherein said drive means comprises a spur gear segment and said feed roller carries a resilient ring positioned for yieldable during engagement by the teeth of said spur gear segment.
 24. The apparatus defined in claim 20, wherein said feed roller carries at least one traction ring adapted for coaction with an idler feed roller to assist in prefeeding the separated top sheet, said traction ring overlying said port and being apertured to expose said port at the periphery thereof.
 25. The apparatus defined in claim 20, wherein said carriage includes: 